Fig 1.
Sampling sites in the North Adriatic Sea.
Map of the Adriatic Sea with details of the sampling sites (star) at the Bernardin harbor (star) and the canal Sv. Jernej (star), Slovenia. The map was created using the GMRT MapTool (www.marine-geo.org/tools/GMRTMapTool [62]).
Fig 2.
Zoothamnium ignavum sp. nov. colonies on sunken wood.
a, c) Z. ignavum sp. nov. colonies, b) top terminal zooid; white arrows denote free-living bacteria colonizing the same wood surfaces as Z. ignavum sp. nov.
Table 1.
Probes used for fluorescence in situ hybridization.
Fig 3.
Drawing of the colony and the microzooids in extended condition. mi: microzooid, ma: macrozooid, ttz: top terminal zooid, tbz: terminal branch zooid, sp: spasmoneme, st: stalk, ad: adhesive disc, pm: paroral membrane (haplokinety), am1: adoral membranelle 1 (polykinety), in: infundibulum, cp: cytopharynx, man: macronucleus, min: micronucleus, fv: food vacuole, cv: contractile vacuole, gr: granules, tl: telotrochal band, b: bacteria.
Fig 4.
Micrographs of living and silver-stained Zoothamnium ignavum sp. nov. colonies.
a, b) General view of living colonies, c) macrozooid, d) stalk with the end of the spasmoneme splitting up into bands, which bundle towards the proximal end of the colony, e) terminal branch zooid, f) microzooid, g-h) oral ciliature of the microzooids. a, b, d) living colonies. c, e-i) silver-stained colonies. ttz: top terminal zooid, tbz: terminal branch zooid, mi: microzooid, ma: macrozooid, sp: spasmoneme, st: stalk, man: macronucleus, min: micronucleus, tl: telotrochal band, pm: paroral membrane (haplokinety), am1-3: adoral membranelles 1–3 (polykineties), s: stomatogenic kinety.
Fig 5.
Schematic illustration of the oral ciliature of the microzooid of Zoothamnium ignavum sp. nov., viewed from the oral pole.
pm: paroral membrane (haplokinety), am1-3: adoral membranelles 1–3 (polykineties), s: stomatogenic kinety.
Table 2.
Colony dimensions and characteristics of Zoothamnium ignavum sp. nov. in comparison to Z. alternans QD and Z. niveum.
st + br + sp: stalk with branches and spasmoneme; st–br + sp: stalk without branches and with spasmoneme; st–br–sp: stalk without branches and spasmoneme.
Fig 6.
Bayesian inference tree inferred from the nucleotide sequences of the small subunit rRNA gene showing the phylogeny of Zoothamnium ignavum sp. nov.
Numbers at nodes represent Bayesian posterior probabilities and ML bootstrap values. The scale bar corresponds to 4 substitutions per 100 nt positions.
Fig 7.
Bayesian inference tree inferred from the nucleotide sequences of the small subunit rRNA gene showing the phylogenetic position of “Candidatus Navis piranensis” gen. nov., sp. nov.
Numbers at nodes represent Bayesian posterior probabilities and ML bootstrap values. The scale bar corresponds to 4 substitutions per 100 nt positions.
Fig 8.
Epi-fluorescent micrographs of the Zoothamnium ignavum sp. nov. symbiosis.
a, b) LIVE/DEAD staining, c, g, k) DAPI (blue), d, h, l) probe ZIS645 in Cy3 (red), e, i, m) EUBmix in Cy5 (green), f, j, n) overlay with differential interference contrast. ma: macrozooid, mi: microzooid, ttz: top terminal zooid, tbz: terminal branch zooid, st: stalk; the white arrows indicate signals observed in food vacuoles (amplified in g-n).
Fig 9.
Scanning electron micrographs of Zoothamnium ignavum sp. nov.
a) Expanded colony, b) contracted colony, c) stalk with bacterial coat, d) aposymbiotic microzooid, e) the two different morphotypes of the ectosymbiont on a microzooid, f) macrozooids, g) oral ciliature of a macrozooid, h) branch with microzooids and the terminal branch zooid. ttz: top terminal zooid, tbz: terminal branch zooid, mi: microzooid, ma: macrozooid, st: stalk, oc: oral ciliature, b: bacteria, br: branch.